Vol. 4] 



Hohvay.—Cold Water Belt. 



265 



of calm water or even counter eddies between. A steamer mov- 

 ing rapidly may pass through several narrow streams of differ- 

 ing velocity or even differing direction and its report of current 

 would then be the algebraic sum of the various currents en- 

 i countered. A becalmed ship or even a slow-moving sailing- 

 ship is apt to remain in one stream for the entire 24 hours. 

 This is supposed to account, for some of the widely differing 

 reports of sailing vessels and of steamers in traversing the same 

 region. With the increasing commerce of the Pacific the num- 

 ber of reports from both steamers and sailing vessels will in- 

 crease, and reasonably correct information will be obtained for 

 the zones traversed by regular vessels. For the parts of the 

 ocean out of the usual courses laid down, reliance must be placed 

 in the scientific expeditions devoted to oceanic research. 



An important addition to the reports of currents encoun- 

 tered by vessels are the so-called "bottle tracks." Bottles 

 usually made of rubber are thrown overboard with an inclosed 

 slip giving the latitude and longitude of the ship at the time. 

 On the bottles is a printed recjuest that they at once be returned 

 to the authority conducting the investigation, with a statement 

 of the time and place of finding. The bottle track is the line 

 connecting the place of starting and the place where found. 

 A minimum rate of drift is thus established. The line of drift 

 and the time that the bottle may be stranded on some coast 

 before being found are the elements of uncertainty. If the 

 bottle is so weighted as to expose practically no surface to the 

 wind, its movement depends entirely on current or drift and 

 "bottle tracks" thus form a valuable element in current deter- 

 mination. 



A third important source of information is found in the 

 constantly growing mass of data on ocean temperatures. The 

 thermometer is one of the most reliable instruments in deter- 

 mining currents. Unfortunately much of the data for ocean 

 temperatures on this coast is scattered through the reports on 

 file in the Hydrographic Office and is not accessible to the 

 public. It is to be hoped that more of this will be tabulated 

 and made available to investigators as has been done by Mr. C. 



